Effective matrix viscosity as a function of melt fraction. Curves calculated using eq. (16) and parameters listed intables 3 and 4 obtained by applying the numerical model to the centrifuge experiments (green lines) and those of Hoyoset al. (2022) (colored thin lines) through MCMC inversions. The solid green line treats \(\xi_{\text{ref}}\) and \(\phi_{m}\ \)as material parameters, while faded green lines and dashed lines treat only\(\phi_{m}\) as a material parameter. These expressions assume that there is no grain boundary-controlled diffusion. Superimposed are effective matrix viscosities (data points) measured from experiments of C423 and C372 of Renner et al. (2003). Solid black line is a fit to C423 and C372 using eq. (20), which assumes experiments are limited by grain boundary-controlled diffusion (no repacking). Eq. (20) is a function of the melt fraction at which the crystal matrix disaggregates and the matrix shear viscosity, here equal to 0.36 and 1012.51, respectively.